Conical mill



H. W. HARDINGE.

CONICAL MILL.

APPLICATION FILED SEPT. 11, 1919.

1,355,474. Patented Oct. 12,1920.

Inventor By Attorneys short cylindrical section Improvements in Conical Mills,

, wall) which may HARRY W. HARDING-E, OF NEW YORK, N. Y.

CONICAL MILL.

Specification of Letters Patent.

Patented Oct. 12, 1920.

Application filed September 11, 1919. Serial No. 323,118.

T 0 all whom it may concern: Be it known that I, HARRY W. HARDINGE, a citizen of the United States, residing at New York, in the county and State of New York, have invented certain new and useful of which the following is a full, clear, and exact description.

The now well known conical mill, for grinding or disintegrating ores and other materials, in its most common form consists of two cones arranged base to base with a between the two. The material to be ground is delivered into one of the cones and the disintegrated ,or ground material is discharged from the other (usually through an axial opening at the apex or through apertures in the therefore be termed the conical outlet portion of the mill. Another form of the conical mill is conoidal in shape, as in Patent No. 1,202,278. In any case the distinguishing characteristic is the tapering form of the outlet portion. This tapering form causes the material (as the mill is revolved on its longitudinal axis) to assume a sort of vertical stratificationor classification according to size, the pieces or masses being largest at the greatest diameter of the mill and decreasing in size progressively toward the apex of the outlet cone, as clearly described in my prior Patent No. 908,861.

Under normal conditions-that is, when the mill is operated at or below the maximum capacity for which it is designed-the assorting of the material according to size permits only particles of the desired fineness to issue from the outlet, but if the material to be reduced or ground is fed at a faster rate, as is often done in the efiort to increase the output, it is found that part of the material discharged, sometimes a considerable part,

is composed of particles too large; for the intended purpose, and in such cases it is necessary to separate the coarse material and return it to the mill for further reduction. My present invention relates to this separation and return of the coarse material, and has for its chief object to provide the mill itself with simple and effective means for the purpose. To this and other ends the invention consists in the novel features and combinations hereafter described.

In carrying out the invention in the preferred manner I provide outside of the conical outlet portions of the mill a conical or even larger,

hood, into which part or all of the more or less disintegrated material is discharged either through an opening at the apex-of the outlet portion or through suitable openings in its wall. This hood is fastened to the outlet portion of the mill in any suitable manner so as to revolve with it. Extending back from the base of the conical or tapering hood I provide one or more pipes leading tothe interior of the mill, preferably at a point in rear of the base of the outlet cone which operate on the principle of the Archimedean screw to return the coarse particles while the fine or finished particles are discharged from the apex of the conical hood or throu h its walls.

Referring now to the accompanying drawing, in which several embodiments of the invention are illustrated, somewhat diagrammatically,

Figure 1 is a side view, partly in longitudinal section, particularly for wet grinding.

Fig. 2 is a similar view of the barrelor drum of a mill designed for definite sizing of the material, particularly in dry grind,- ing. 7

Fig. 3 is a longitudinal section of a form in which all the disintegrated material is discharged from the apex of the conical outlet portion of the barrel.

In the mills illustrated, 10 designates the conical inlet portion, provided'with an axial.

inlet trunnion 11 through which the material to be ground is introduced. 12 conical or tapering outlet portion, which may be provided with an axial outlet trunnion 13. The barrel or drum, composed of the two cones (and, in thepresent instance,

an intermediate cylindrical part 14) may be mounted in suitable bearings for rotation on its trunnions, as in Figs. 1 and 2, or, where the outlet trunnion is omitted, the barrel may be supported by the inlet trunnion and by a rin as 15, Fig. 3. A gear 16 (not shown inig. 2) is provided to rotate the barrel.

Referring to Fig. 1, the conical outlet portion 12 is provided with outlet openings 17 of suitable size to discharge fine or finished particles and also coarse particles .up to a certain size, say an eighth of an inch,

in diameter, so that fine material may be discharged not only from the outlet trunnion 13 into the launder 18 but also (together with coarse material) through showing a form designed is the hood 19.

particles flow over the edge at the apex with the Water into the launder 20, while the larger and therefore heavier particles sink to the bottom and collect at the base of the, hood. 'Here they enter the ,helical conveyer pipe 21 and as the mill revolves are carried back and discharged into the interior for further-reduction.

Where a definite sizing of the finished material is desired, and especially where the material isto be ground in the dry state, the classifying hood is made of foraminous materialfjfor example a screen of woven wire of suitable mesh; as 22, Fig. 2. In this case fine particles sift through the screen into the receiving hopper 23. In F igi .3 the conical outlet portion'12 is iniperforate, and all the material is discharged from the apex into the classifying .turned to the mill by hood 24, which -may be made proportion- 1 and 2. -From the hood-24 the fine, fin shed particles flow over the edge intothe'launder 25 while the heavier, coarse particles sink and are refurther reduction as in Figs. 1 and 2.

It is to be understood that the invention is not limited to the herein described but can be embodied in other forms Without departure from its spirit.

Iclaim:' v a I 1. In a conical mill, the combination with a rotating barrel or drum having a conical outlet portion, of a classif ing hood carried by the barrel or drum an surrounding the conical outlet portion only and rotating therewith to receive coarse and fine material therefrom and adapted to discharge only the hood to receive the fine material, and means at the base of.

coarse or over-size material and return the same to the barrel or drum for further reduction.

2. In a conical mill, the combination with a rotating barrel or drum having a conical outlet portion, of a conical classifyinghood carried by the barrel or drum and surrounding the conical outlet portion to receive therefrom coarse 'and fine material and adapted to discharge only the fine material, and a conveyer pipe extending from the base of the conical hood In the latter the fine, finished,

the conveyer. 26 for a rotating speclfic constructions 1 nation, a rotatable ing hood'secured tosai and discharging into the barrel or drum to return thereto the coarse or over-size particles for regrinding.-

3. In a conical mill, the combination with a rotating barrel or drum having a perforated conical outlet'portion, of a conical classifyi hood carried by the barrel or drum an surrounding the conical outlet portion only to receive coarse and fine ma-' tions therein and adapted to discharge only the fine material, and a pipe extendingfrom the and discharging into the return the coarse material thereto for regrinding.

5. In a conical mill, the combination with barrel or drum having a conical outlet portion, of a conical classifying hood of foraminous material carried b the barhelical conveyer base of the hood rel or drum and surrounding t e conical outlet portion only to receive coarse and fine material therefrom and adapted to'discharge only the fine material, and means at the base of the hood to-receive coarse material and return the same to the barrel or drum for re rindin 6. A grin mg m1 1 comprising in combimeans,'comprising a conical outlet portion, for preventing oversize material from leaving the drum when the mill is operated at or below a predetermined ca drum and surrounding the conical outlet portion thereof to receive oversize and fine material therefrom when the mill is operated above said predetermined capacit nected to said hood an drum for returning the oversize to said mill for regrinding.

In testimony whereof I hereunto aflix mysignature.

* -HARR Y W. HARDINGE.

acity, a classifyand means con-' barrel or drum to drum provided with 

